A large segment of the population have chronic back problems which cause pain and disability. The cause of back pain is often the result of diseased disc material between opposing vertebrae. The diseased disc material usually causes pain because the disc material inadequately supports the opposing vertebrae, thereby allowing the space between the vertebrae to collapse and irritate or damage spinal nerves.
Surgical techniques have been developed to eliminate the persistent pain resulting from diseased disc material. In such techniques, the diseased disc material is removed and the joint between opposing vertebral bodies is fused. Fusion specifically involves removing the diseased disc, preparing a bore for receiving an implant, and inserting the implant between the opposing vertebral bodies.
Spinal fusion implants and the surgical instruments used for implanting these fusion implants are well known in the art. The surgical instruments required for preparing the disc space typically include one or more distractors, drills, reamers, and other instruments.
These prior art instrument sets typically prepare a cylindrical contact area for the fusion implant or artificial disc. Such an instrument set is described in U.S. Pat. No. 5,505,732, to Michelson. The use of a cylindrical shape within the disc space does not restore the natural lordosis of the lumbar and cervical spine, but instead, undesirably establishes a relative kyphosis.
Accordingly, an instrument system is needed for preparing a disc space between adjacent vertebral bodies in a manner that restores the natural lordosis of the lumbar and cervical spine, so that a repair device can be inserted therein.